G&G Viper - removing front RIS?

[Apharmd]

Hi guys, it seems I only really post if I'm having issues, sorry about that.

I bought a G&G M4 Viper a few weeks ago, intending to install a G&P Patriot front end and make something partially resembling a MGS3 Patriot.

The problem is, I have no idea how the front RIS is meant to come off. I've looked around online, but there's no disassembly guides for the Viper or the Cannon (Which IIRC uses the same rail system).

Anyone modded one of these before who can help?

Thanks for your time.